ABSTRACT The multilayer soil structure model is the fundament to design grounding systems. A fast algorithm is presented to invert the structure parameters of the horizontal multilayer soil. The procedure is divided into two independent stages. First, Fredholm equation of the first kind with respect to the apparent resistivity is solved by using the technology of decay spectrum, which can reduce the computation time greatly. Second, the structure parameter of soil is determined by the generalized Newton-Kantorovich method, which is more robust and less noise sensitive because of using the generalized inverse algorithm to solve the nonlinear equation system. The numerical results show the validities and main features of the proposed approach. The numerical results by using the proposed method are in a good agreement with ones from geophysical exploration.

[Show abstract][Hide abstract]ABSTRACT: Grounding grid is an important guarantee for safe operation of transformer substation, and its performance has been under the attention of the appropriate departments. When the power system is in contingency, grounding grid will rapidly excrete fault current into the earth in order to control the rise of maximum of potential and ensure the safety of person and equipment. To make the superficial potential distributed and further reduce the touch voltage and step voltage so that we can better guarantee the personal and equipment safety, this paper puts forward the optimizing design scheme which uses numerical simulation to analyze the association factor and influencing factor.

[Show abstract][Hide abstract]ABSTRACT: In the most actual grounding project, we always come across a block or some blocks of soil whose resistivity is higher than that of soil surrounding them, that is heterogeneous soil. Effects on grounding resistance by heterogeneous soil under different conditions are different. On the basis of simulation by grounding analyzing engineering software CDEGS, this paper analyses effects on grounding resistance by heterogeneous soil under conditions of different surrounding soil resistivity, as well as different section area size, depth and thickness of heterogeneous soil, all of which provides evidence for building more accurate soil model in the grounding design under complex soil situation.

[Show abstract][Hide abstract]ABSTRACT: Controlled Source Audio-frequency Magneto-telluric (CSAMT) that is used successfully in exploring coal, oil, gas and other resources is a way of geophysical technology, the most important feature of which is that only changing the frequency of field source can soil resistivity of different depth be obtained fully. Firstly, the basic principle of CSAMT for measuring soil resistivity is introduced, and then computer simulation models are built based on CSAMT and Schlumberger method which is accurate and used more nowadays to validate the effectiveness of CSAMT method. On condition of homogeneous half-space, the above models are realized by grounding analyzing engineering package CDEGS. The result shows that the soil resistivity measured by CSAMT can maintain constant in a wide range of frequency and is more close to real value; while the one measured by Schlumberger has a larger error and is even unbelievable when the frequency is higher. So the CSAMT method is more precise than Schlumberger method.

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